<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .float-box {
            /* opacity: 0; */
            float: left;
            width: 100px;
            height: 100px;
            background-color: lightblue;
        }

        .bfc {
            /* opacity: 0; */
            visibility: visible;
            overflow: hidden;
            /* 创建BFC */
            border: 1px solid black;
        }

        .box1,
        .box2,
        .box3 {
            /* opacity: 1; */
            visibility: visible;
            width: 100px;
            height: 100px;
            margin: 10px;
            background-color: lightgreen;
        }
    </style>
</head>

<body>
    <div class="float-box">Float Box</div>
    <div class="bfc">
        <div class="box1">Box 1</div>
        <div class="box2">Box 2</div>
        <div class="box3">Box 3</div>
    </div>
</body>

</html>